Wired to kill: are murderers born or made?

Death-row inmate and convicted murderer Michael Perry, who is interviewed in Werner Herzog’s film Into the Abyss.
Photo: NYT

by
Daniel Dennet

Monsters have always fascinated us. As soon as we outgrow the spine-tingling dragons and ogres of fairytales, we turn our rapt attention to the celebrity monsters of real life: Jack the Ripper, the Unabomber, Charles Manson, Ted Bundy, Adam Lanza. We know their names, don’t we? Behind the voyeurism that tempts even the most “mature" minds lurks a nagging suspicion that there might be something deeply wrong in our righteous reaction to wrongdoers. Who are we to condemn them? If they’ve got a screw loose, shouldn’t they get treatment instead of punishment? And aren’t we just lucky not to have the same urges that drive them?

Then there is the question of how to explain the violent actions of human beings. Do our genes make us do it? Does an abusive childhood and poverty make us do it? Does a culture that glorifies violence make us do it? Whatever long-range effects can be attributed to these background conditions, when push comes to shove, our brains make us do it. All the causes have to be squeezed through the bottleneck of our nervous systems one way or another, and aren’t we learning from the triumphant march of neuroscience that we don’t have the minds we thought we did?

Tom Wolfe
, as always an astute commentator on the current scene, has observed: “The conclusion people out beyond the laboratory walls are drawing is: ‘The fix is in. We’re all hard-wired’ and ‘Don’t blame me; I’m wired wrong’" And the comic strip Dilbert, another sensitive barometer, more recently opined: “Free will is an illusion. Humans are nothing but moist robots. Just relax and let it happen."

Are they right? Will there be nothing left of our freedom and dignity, our responsibility or our autonomy once neuroscience explains the networks of causation inside our brains? When autopsies reveal clear signs of damage in the brains of monsters, what does that portend for the rest of us moist robots? And does this mean our vaunted edifice of law and order is no more defensible than witch trials and exorcisms?

It is hard to think calmly about violence, and nobody knows that better than
Adrian Raine
, a distinguished neuroscientist who has devoted his career to uncovering the causes of human violence. He recognises these are not just scientific questions, like uncovering the causal mechanisms of earthquakes, but also some of the most important ethical questions facing society. And he is all too familiar with the forces that distort thinking by laypeople and scientists alike, having worked into a headwind of scepticism and opposition for decades. Many different sorts of people do not want science poking around their most cherished verities. Consider this unholy alliance of opponents: religious conservatives who see a threat to their Abrahamic vision of retributive justice, liberal legal scholars and philosophers who fear that neurobabble and psychobabble will unweave the fabric of responsibility on which civilisation depends; postmodernists who preach that the concept of scientific evidence is a quaint relic of more innocent times; whole schools of so-called social science whose ideologies are threatened by real science encroaching on their turf. Then there are the journalists, salivating for eye-catching headline opportunities.

Biology is not destiny

The message of this important book affirms what ought to be obvious but is all too often obscured by ideological smokescreens, together with an articulation of what follows from this undeniable truth: every act we ever perform, whether we are sane, normal citizens or serial killers, is the physical effect of a complex combination of genetic, developmental and experiential factors that make us who and what we are at the moment of action. None of us is miraculously isolated from these causal factors – nor should we want to be – but some of us are better “wired" than others. Some of us are indeed “wired wrong" in ways that science can uncover and confirm and in some instances fix. The good news, which Raine is intent on conveying to us, is that “biology is not destiny". While it is true that there really are genetic biases for criminality and violence, it is also true that these genetic biases are not dictatorial and immutable; because our characters are the product of many complex factors, the undesirable tendencies inherent in some of our genes can in principle be neutralised by intervening in the non-genetic components.

Looking at the emerging details of the causal pathways shows how this can be done. A “well-wired" brain must be balanced, and it’s a rather delicate balance, maintained by cascades of neuromodulators and neurotransmitters, each of which is regulated by others, focusing attention, damping urges, stoking desires, calming and stimulating in turn. It can seem a wonder that anybody can get through the day without going berserk, yet most of us maintain a quite robust and reliable degree of self-control, responding appropriately to setbacks and risks and not even tempted by opportunities to commit crimes that are literally unthinkable – by us.

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The ideal of the well-governed mind has been articulated by thinkers since Plato, and we’re now learning how the internal economy and politics of the brain achieve this salutary state – and how we can often intervene to restore it when a brain goes bad. It is quite easy to see how a small genetic difference (an allele, a mutant form of a normal gene) can put a brain into imbalance, much the way alcohol or drugs can, by flooding it with too much of one neuromodulator or starving it of one that puts on the brakes. Once an imbalance is discovered and understood, the road to treatment can be explored, and it might involve directly supplying the lacking chemical, or adjusting the environmental conditions that normally provoke its production, or both. Sometimes the root cause of the imbalance is an anatomical defect in the brain – a stunted or overdeveloped region. This is harder to fix but there are work-arounds. The brain is a spectacularly versatile and opportunistic finder of new pathways if given half a chance. But some brains are beyond repair – now and probably forever.

What should we do about all this? Would it be best to replace our system of law and punishment with a treatment model in which people are no more held responsible for their crimes than they are for cancers or heart attacks? Some neuroscientists, psychologists and philosophers have been beating the drum for this revolutionary vision and one might think Raine would be at the head of the parade, but he has been working on these issues for longer than most of them and takes a more circumspect approach. There are different kinds of ways that brains get people into trouble, and they require different approaches. There are “hot-blooded" criminals and “cold-blooded" criminals, for instance, and the physiological differences between them are even more salient than blood temperatures would be. He tentatively presents more nuanced prescriptions.

The heart rate gives it away

Tradition (or better, ancient myth) has it that you have free will only if your decisions are not caused or determined by antecedent conditions. That variety of free will is as illusory as poltergeists, but we don’t want to replace one profoundly unscientific ideology with another oversimplified “scientific" or “medical" ideology, according to which nobody is ever responsible for what they do because everybody’s decisions have a cause. We need to understand how people’s decisions are caused if we want to identify those who are “wired wrong". In our desire to base our policies on facts established by scientific research, we must be patient and scrupulous, and not jump to conclusions inspired by a few anecdotes or single studies.

One of the strengths of the book is Raine’s careful presentation and explanation of the evidence that supports his striking claims. He knows most laypeople and not a few scientists routinely misinterpret statistical evidence, so he is careful to provide perspective. Lower resting heart rate in youngsters has a surprisingly strong correlation with “delinquent, criminal and violent behaviour" in adults. How strong? Raine cites a study by David Farrington of Cambridge University which claims “low heart rate was even more strongly related to measures of violence than having a criminal parent – one of the best social predictors of later crime". If we look at resting heart rate when given a “stressor" (a demanding task, such as counting backwards from 100 by 7), low heart rate is a predictor “as strong as the ability of mammograms to detect breast cancer". Meta-analyses (critical surveys reviewing the studies in an area)confirm the relationship, showing it is a better predictor than any other that has been found to date, and at least one meta-analysis shows prescribing stimulants to raise heart rate in youngsters diminishes later antisocial behaviour.

Raine goes out of his way to forestall misinterpretation, but not always far enough. One study recounted at some length compared thousands of Danish babies over 18 years and divided them into four groups: those with birth complications, those who had been rejected by their mothers, those with neither of those misfortunes and those with both. “The first three groups did not differ significantly from each other, with rates of violence at about 3 per cent. It was the fourth biosocial group – the one with both the biological and the social hits – that had the highest rates of violence. This group had three times the average of the other three groups – 9 per cent of them became violent offenders." Three times! Yes, but notice: even in that group, nine out of ten babies burdened with both birth complications and maternal rejection did not exhibit any violence in young adulthood. (Raine’s main claim is secure: factors can multiply the risks, even if they don’t always.) Similarly, he points out that a female schizophrenic is 22 times more likely to kill than a non-schizophrenic female, but still, as he observes, the vast majority of schizophrenic females are not killers.

This pattern of vast normality (most people are non-violent) despite significant predictors at the margins is ubiquitous in research on violence but tends to be overlooked, distorting public imagination. Only a small minority of adults exhibit signs of pathology or even deficiency, and a small proportion of those turn out to be criminals. Just as important, not all criminals show signs of brain defect.

In an unusual lapse, Raine indulges in a serious overstatement: “Criminals do have broken brains, brains that are physically different from those of the rest of us." All of them? No, he hasn’t come close to establishing that – or even trying to establish that. This is important, because there is a tendency in discussions of law and punishment to surmise that anybody who isn’t deterred by the risk of punishment on some occasion must have some sort of broken brain; they must be undeterrable. This is a mistake. The reliability of self-control on which the law depends, for instance, is not perfect reliability – thank goodness, since none of us could meet that standard. What Raine is talking about, as he occasionally makes explicit, is recidivist criminals, those who demonstrate time and again that they are not deterred by the threat of punishment.

Waiting for the milk to spill

And now we face the fundamental quandary that besets any project to reform our system of punishment with measures that take proper account of incapacities while protecting civil liberties. You can’t identify recidivist criminals until after they have committed numerous crimes. Nobody is a likely recidivist in advance of committing a crime. That is to say, even the best predictors so far uncovered don’t raise the probabilities above a coin flip. Raine would like to intervene early, to prevent violence, instead of just responding after violence has occurred: “We can wait until the milk is already spilled and we have to deal with the adult recidivistic offender who is so very hard to change" or we can follow his advice and intervene as early as possible, while brains are young and labile. This makes fine sense as long as the interventions are not freedom-limiting, or stigmatising. Let’s eliminate lead from the environment as fast as we can, since it has a demonstrated harmful effect on young brains, and let’s also respond swiftly to curb child abuse and poverty, clearly marked as predictors of later violence. But what are we to do about those interventions that would require identifying children with the relevant brain conditions and subjecting them (involuntarily) to treatments that might well save them from a life of lawbreaking and prison? “At what cost civil liberties?" Raine asks. But he attempts only half the answer.

He makes sure we know the likely benefits by describing a future, in lively detail, of just such a project. He calls it the LOMBROSO programme, an acronym for Legal Offensive on Murder: Brain Research Operations for the Screening of Offenders, but more pointedly he has named it after Cesare Lombroso, the 19th-century phrenologist and criminologist who first proposed that “criminal brains" could be identified. It is courageous – or maybe just rash – of Raine to name his pet project after a figure whom textbooks typically revile, but there is a method to be discerned here and it should be taken seriously. Knowing that his readers will be on high alert, ready to pounce on any telltale symptom of political incorrectness, he chooses to brandish his challenges, apparently confirming the worst fears of his readers. Then, that settled, he gets them to think clearly about what really might be good or bad about one policy or another. It works – at least most of the time. He uses this strategy in both directions, providing a ringing defence of retributive punishment – easing the anxiety of retributivists and showing that he really understands where they are coming from – before calmly dismantling it, showing where the weaknesses lie.

Gritty details

Raine wants us to think about a disturbing topic, and has chosen – wisely, I think – to live dangerously; to confront the reader with a remorseless clinical objectivity about the details of unspeakable atrocities, with occasionally over-casual formulations that seem designed to provoke outrage from those who think such taboo topics should be handled with the utmost decorum and gravity. He clearly enjoys the role of museum-guide in the macabre chamber of horrors where the exhibits are real-life cannibals, heartless psychopaths, child killers in both senses of that ambiguous phrase, and other walking time-bombs. He uses our relish for such fare to propel the reader through the patient explanation of the methods of brain scanning, the recitation of statistics and the meta-analyses. It is Raine who arranged to scan the brains of 41 murderers on death row, with significant and disturbing results. Murderers from “good homes," for instance, showed significantly reduced frontal lobe activity compared with murderers who had deprived upbringings. Should we draw the conclusion that children from good homes grow up to be murderers only if they have broken brains? No. It could be that murderers with good brains from good homes don’t get caught. It’s complicated.

An even more audacious study, published in 2000, was one he conducted with “free range," “successful" psychopaths – never arrested for any crime, never before identified in the wild. How on earth did he find them? An educated hunch suggested that a significant proportion of male temp workers would be psychopaths, so he got a grant that permitted him to hire dozens of them in the Los Angeles area. Their job: to fill out questionnaires and in some instances have their brains scanned, then participate in interviews. Sure enough, 21 men (and no women) qualified as “psycopaths" on the standard test used in prisons. Their brains were scanned and they showed the telltale prefrontal deficiency in grey matter as well as other well-established markers of psychopathy. The interviews were the most striking aspect of the study. None of the 21 had criminal records, but reassured by the certificate of confidentiality Raine secured for the experiment (a standard provision where subjects could be at risk otherwise), they readily provided detailed accounts of the crimes they had committed, including armed robbery, rape and even murder. Raine thinks there is scant chance that they were making any of this up, and he has perhaps more experience than any other researcher in talking with violent criminals. “Perhaps for the first time in their lives, they could talk about their wrongdoings at length with a professional in full confidence and without risk – even getting into the nitty-gritty of rape and homicide."

He eventually briefly confronts the fear that, once on the slippery slope he has embarked on, scientific research into the links between our brains and our tendency towards violence will bring about the demise of moral responsibility altogether. He calls the fear a “cop-out," arguing that “there is firm ground underfoot and ample opportunities up and down that slope to choose where to stand – if we have the courage to do so". But that is not enough, because courage isn’t in short supply; what we need are good reasons, and he doesn’t provide so much as a hint as to what the grounds will be for taking a stand in one place rather than another.

Punishment v retribution

We need a clear account of what moral responsibility requires and although Raine takes a few stabs at the free will issues, he wisely retreats. (If only the other neuroscientists confronting this tangled philosophical mess were as circumspect!) This is not his area of expertise, so he leaves the issue unresolved. The main obstacle to his understanding, I submit, is his failure to discern the difference between a retributive justification of punishment (which he is right to dismiss) and a consequentialist justification of punishment.

Some thinkers – even some philosophers – make the mistake of equating punishment with retribution: an eye for an eye, a tooth for a tooth, with no concern for the consequences. The retributivists say “we should punish wrongdoers simply because they deserve to suffer, even if punishment doesn’t deter them or others". The consequentialist says that the institution of punishment has a moral justification in virtue of its fostering respect for the law. We don’t just try to “fix" wrongdoers; we punish them, whether or not this improves them, in order to maintain the rule of law. (Handing out a red card in football may have the effect of reforming the offending player, but that is not the consequence that matters; the game is made better if everybody plays by the rules.) Such a consequentialist justification of punishment can define a defensible class of responsible citizens, who, if they transgress, are eligible for punishment, not treatment, because they are, in general, reliably deterrable. But demonstrating this to the satisfaction of the corps of philosophers and legal scholars wrestling with the issue is a job for another book by another author.

The Anatomy of Violence is a most valuable contribution to the current debates on these topics. Raine provides the details, and the evidential backing, for a host of distinctions that need to be drawn by those of us intent on reforming our obscenely unjust system of criminal justice. His ultimate reticence on the big ethical and legal questions is itself not an abdication but a measure of his own sense of responsibility: he tells us about what he can responsibly vouch for, and invites us to finish the story using our own expertise. That is perhaps the most important task facing philosophy and jurisprudence.